1. Field of the Invention
The present invention relates to a medical device for draining fluid from the body cavity of a patient, and particularly to a drainage apparatus having a water seal chamber that restricts and channels the passage of fluid. More specifically, the present invention relates to a dual port arrangement for a water seal chamber that prevents the breach of the water seal during reverse flow conditions inside the drainage device.
2. Prior Art
A drainage device is an apparatus for suctioning gases and liquids from the pleural cavity of patients. The pleural cavity lies within the rib cage above the diaphragm and is surrounded by the pleural membrane. The pleural cavity contains both lungs, which in their normal expanded state fill the pleural cavity. Several conditions and diseases such as interventional surgery, trauma, emphysema and various infections can cause a build up of liquid and gases around the lungs in the pleural cavity. When this occurs, it causes the lungs to collapse to a volume much less than that of the pleural cavity, thereby severely impairing the breathing functions of the patient. The lungs can be re-expanded to their normal state to fill the pleural cavity by draining the liquid and gases from the pleural cavity using a drainage device.
Drainage devices are also used during autotransfusion for recovering autologuous blood from the patient""s pleural and mediastinal cavities and transfusing that blood back into the patient. Autotransfusion using recovered autologuous blood offers significant advantages over normal transfusion procedures which use homologous blood from other humans. Autologuous blood reinfused back into the patient reduces the risk of adverse reactions by the patient and transmission of infectious disease while supplying a readily available source of compatible blood to the patient.
Various drainage devices have been developed to drain and collect fluid from the pleural cavity of a patient for subsequent reinfusion back into the patient. U.S. Pat. No. 4,857,042 to Schneider illustrates the prior art development of drainage devices. The Schneider device comprises a closed vessel which includes a collection chamber for the collection of fluid from the pleural cavity, a water seal chamber for preventing passage of gas from the atmosphere into the patient""s pleural and mediastinal cavities, and a manometer chamber for regulating the degree of vacuum in the drainage device. The water seal chamber is a U-shaped chamber having two vertical arms that meet through a single port located at a bottom portion of the water seal chamber. A predetermined amount of water, called the water seal, is disposed along the bottom portion of the U-shaped chamber which functions as a one-way barrier that effectively separates one arm of the chamber from the other arm such that gas and atmospheric air are prevented from flowing into the collection chamber, while permitting gas to exit therefrom. The water seal chamber is configured so that the arm upstream of the water seal chamber communicates directly with the collection chamber of the drainage device and the downstream arm of the water seal chamber communicates either with a suction source when the drainage device is used in a vacuum drainage mode or atmosphere when the device is used in a gravity drainage mode. When the drainage device is used in the vacuum drainage mode, the health care practitioner applies a source of suction to the suction port which causes a low pressure area to be established between the water seal and the suction control chamber and a negative pressure range to be maintained inside the collection chamber. Maintaining a negative pressure range inside the collection chamber causes shed fluids to be evacuated from the pleural cavity of a patient and deposited inside the collection chamber. In the gravity drain mode, no vacuum is applied to the drainage device and only a small negative pressure generated by the patient""s inhalations is present in the collection chamber. To drain the pleural cavity of fluid, the drainage device is located below the patient such that the force of gravity in combination with the small negative pressure in the collection chamber draws shed fluid from the patient and into the drainage device. A collection port is provided along the surface of the collection chamber for the entry of shed blood and gases drained from the patient""s pleural cavity through a thoracotomy tube and deposited inside the collection chamber. The drainage device may also be connected to a blood compatible pump for pumping autologuous blood through an outlet port provided along the surface of the collection chamber for reinfusion back into the patient when the drainage device is used for autotransfusion.
The Schnieder device is also provided with a valve mechanism above the water seal chamber to permit the passage of fluid from the water seal chamber in the event of a sudden increase in negative pressure inside the collection chamber, such as when the patient deeply inhales during breathing exercises. Unfortunately, a rather deep and quick inhalation by the patient, or a manual stripping of the patient""s thoracotomy tube by a health care practitioner running his or her hands along the tube in order to remove blood clots formed along the tube, may cause a sudden breach in the water seal which the valve mechanism of Schneider is not designed to prevent. A breach of the water seal occurs when negative pressure inside the collection chamber is abruptly increased by the aforementioned causes. This sudden increase in negative pressure inside the collection chamber causes reverse flow conditions inside the drainage device which produces a deep water gradient or plane that breaches the water seal and permits gases to rush from the downstream arm of the water seal chamber to the upstream arm. This reverse flow condition forces the level of the water seal at the downstream arm down below the upper portion of the water seal port and causes the breach the water seal. Reverse flow conditions occur whenever the negative pressure within the upstream arm becomes greater than the negative pressure in the downstream arm. This change in pressure causes the normal fluid flow from the upstream arm to downstream arm to reverse direction. When the water seal is breached during reverse flow conditions gases are permitted to freely flow through the water seal port above the water seal towards the upstream arm of the water seal chamber which communicates with the collection chamber. Such free flow of gases into the collection chamber is deemed undesirable since it lowers the generally constant negative pressure required to be maintained inside the collection chamber which communicates directly with the patent""s pleural cavity. The sudden flow of gases through a breach in the water seal has a negative impact on the patient during convalescence because the lowering of the negative pressure range usually maintained in the collection chamber inhibits the patient from properly expanding his lungs. When the negative pressure maintained inside the collection chamber is decreased below this predetermined negative pressure range, it makes it more difficult for the patient to fully expand his lungs during inhalation exercises and unnecessarily lengthens the time of convalescence. Moreover, gases flowing into the collection chamber during reverse flow conditions may be visually undesirable to the patient because gas flow through the water seal during reverse flow conditions causes a migration of bubbles towards the upstream arm which can be seen through the transparent body of the closed vessel and may give the patient the incorrect perception that the drainage device is not operating correctly.
It has been found that the configuration of the single port arrangement used to separate the two arms of the water seal chamber in prior art drainage devices is insufficient to prevent breach of the water seal caused by reverse flow conditions during a sudden deep inhalation by the patient or manual stripping of the thoracatic tube by a health care practitioner. Therefore, there is a need in the art for a drainage device which includes an improved water seal port arrangement that substantially prevents the breach of the water seal during the reverse flow conditions.
In brief summary, the present invention overcomes and substantially alleviates the deficiencies in the prior art by providing a novel dual port arrangement for a water seal chamber adapted for substantially preventing the migration of gas bubbles through the water seal and the breach of the water seal in a medical drainage device during reverse flow conditions. The dual port arrangement according to the present invention comprises an upper side port and a lower tunnel port which both communicate with the upstream and downstream arms of the water seal chamber. The side port has a narrow slot configuration that extends along a portion of the water seal chamber side wall that separates the upstream and downstream arms. On the other hand, the tunnel port defines a low profile, elongated conduit that extends along the bottom portion and through the back wall of the water seal chamber.
The narrow slot configuration of the side port functions to restrict fluid flow communication through the side port and greatly inhibit the breach of the water seal during reverse flow conditions when incoming fluid flow into the collection chamber forces the water seal into a steep water gradient profile at the downstream arm and forces the level of the water seal to fall below the upper portion of the water chamber port found in the prior art device. The configuration of dual port arrangement of the present invention channels restricts fluid flow and fluid through two alternative ports in the water seal chamber which greatly inhibits the breach of the water seal during reverse flow conditions. Further, the elongated conduit defined by the tunnel port provides a sufficient conduit for the evacuation of fluid from the collection chamber during normal operation of the drainage device while being configured to substantially inhibit the deep water gradient of the water seal from falling below the upper portion of tunnel port and cause the breach the water seal during reverse flow conditions. This is accomplished by locating the elongated conduit of the tunnel port along the bottom portion of the water seal chamber with one end of the tunnel in communication with the downstream arm and the other end of the tunnel in communication with the upstream arm of the water seal chamber. The elongated conduit presents a low profile relative to the rest of the water seal chamber which greatly inhibits a steep water gradient from falling completely below the upper portion of the tunnel. It is this combination of a side port with a restricted flow rate and a tunnel port having a low profile, elongated configuration that provides a means for channeling fluid flow through the water seal chamber such that a deep water gradient is unable to cause a breach of the water seal during reverse flow conditions.
Accordingly, the primary object of the present invention is to provide a multi-port arrangement between two arms of a water seal chamber of a drainage device configured to prevent breach of the water seal during reverse flow conditions caused by an increase in negative pressure inside the collection chamber.
Another object of the present invention is to provide an elongated, low profile conduit for channeling fluid flow through the water seal chamber.
A further object of the present invention is to provide an elongated, low profile conduit which permits sufficient fluid flow through the port during normal operation of the drainage device while preventing the breach of the water seal during reverse flow conditions.
Another further object of the present invention is to provide a dual port arrangement for restricting the flow of fluid through the water seal chamber.
These and other objects of the present invention are realized in the preferred embodiment of the present invention, described by way of example and not by way of limitation, which provides for medical drainage device having a dual port arrangement that prevents breach of the water seal during reverse flow conditions.
Additional objects, advantages and novel features of the invention will be set forth in the description which follows, and will become apparent to those skilled in the art upon examination of the following more detailed description and drawings in which like elements of the invention are similarly numbered throughout.